class_docstr: The Sacred Mongo client allows to retrieve results from experiments tracked
  with Sacred from MongoDB.
code: def __len__(self) -> int:
      return self.db.runs.count_documents(self.base_query)
  
file_path: gluonts/src/gluonts/nursery/tsbench/src/tsbench/analysis/tracking/client.py
imports: from typing import Any, Dict, Iterator, List, Optional, Union
  import gridfs
  import pymongo
  from .experiment import SacredExperiment
label_desc: Use image node_id 5 for calling the SacredMongoClient obj's underlying member method code with example usage: obj.__len__() and returns: self